As human population grows, as human population's standard of living improves resulting in more use of Earth's resources, and Earth's resources become increasing depleted with progression of time, there arises an increased need to recycle materials and reduce generation of waste. Moreover, there is also an increasing need to ensure that such recycling is executed in a manner which itself employs as few resources as possible, namely in manner which is most efficient.
In technologically-advanced countries, waste management industries are growing in importance and need to employ increasingly efficient processes to increase revenue margins, namely such waste management industries need to optimize their resource utilization, for example use of waste collection vehicles, use of waste collection personnel and similar. Based upon contemporary data from Environmental Business International, the United States of America (USA) has a solid-waste management industry which has grown in value from 39.4 billion US dollars in the year 2000 to 52.40 billion US dollars in the year 2010.
An effective manner to increase operating efficiency in waste management industries is to implement waste containers, namely “trash containers”, in a smart manner. Such a smart manner requires one or more sensor devices to be attached to each waste container, wherein the one or more sensor devices are wireless-enabled for communicating to a waste-collection coordinating arrangement, for example a waste-collection control centre, and one or more sensors for sensing a quantity and/or state of waste in the container. Moreover, there is also a need to be able to retrofit such one or more sensor devices to existing waste containers to convert them to being smart waste containers.
Several problems are encountered in practice when implementing an aforementioned waste management system employing a plurality of smart waste containers which are spatially distributed at customer premises. A first problem arising is that the waste containers themselves are often housed outside buildings and hence subject to extremes of weather conditions, for example sub-zero temperatures in winter, and elevated temperatures in summer due to incident solar radiation thereupon; in consequence, their sensor devices need to be able to function over a wide range of environmental temperatures. A second problem is that waste containers often need to be substantially sealed when in a closed state, for example to prevent animals such as rats, mice and insects gaining access to contents of the waste containers that could result in a public health risk; when wet waste is placed into the waste containers, a humidity within the waste containers is potentially high, with a risk of condensation occurring on an inside lid surface and walls of the waste containers, for example when a sudden fall in external temperature outside the waste containers occurs, for example at dusk after a warm summer day. A third problem encountered is that contemporary waste containers are often fabricated from molded plastics materials which are effective thermal insulators, such that internal volumes of the waste containers, especially lid regions thereof, can potentially become very high when the waste containers are exposed to strong sunlight having an energy density of circa 500 W/m2 to 1000 W/m2. A fourth problem encountered is that it is highly desirable that the sensor devices be retrofitted to existing waste containers to render them as smart containers at their locations of deployment, namely installed in situ, thereby avoiding a need to transport the waste containers to a fitting centre to have their sensor devices fitted, and then transport the waste containers back to their respective deployment locations again; beneficially, fitting of the sensor devices is executable by a single member of personnel, even when large waste containers having lids with areas in excess of 1 m2 are to be retrofitted with one or more sensor devices.
Known sensor devices for implementing smart waste containers are not able to address the aforementioned problems in a satisfactory manner.
In a published Japanese patent publication no. JP09144712A (Koganei Corp.), there is described a mounting structure for a sensor switch. The mounting structure includes a sensor holder which is fixed to a mounted member by employing a screw. Moreover, the sensor switch is installed into the sensor holder by pressing it against the sensor holder, wherein the sensor holder flexes to receive the sensor switch in a secure manner. Although such a mounting structure is suitable for installation of a sensor switch, it is unsuitable for use with the one or more aforementioned one or more sensor devices required for implementing a smart waste container. Document WO 2012/015664 presents a waste enclosure device comprising a waste enclosure employing operational functions including collection and monitoring capacity wherein said device includes one or more programmable logic controllers. Operational functions are performed by electrical components including sensors to determine waste deposits characteristics and contents. Said device operational functions are further adapted to send and receive data, optionally wirelessly, and configured and adapted to utilize solar derived electric power and, optionally, electric power from other sources. Document WO 2011/058287 discloses a device for measuring a filling rate of a container comprising: an attachment means suitable for attaching the device to an inner surface of the container; a sensor suitable for measuring said filling rate and generating data; an electronic module comprising a clock and a telecommunication means and being suitable for triggering the sensor, receiving and sending the data to a remote apparatus; and a source suitable for supplying electric power to the electronic module and the sensor. Document DE 20210495 shows a plastic molded wheeled waste bin having a flexible electrical resistance sensor which conveys a value to a transmitter unit on the outside of the rear wall which inductively communicates with a receiver unit on the collection vehicle to indicate the capacity of the contents. Document U.S. Pat. No. 4,282,591 discusses a light control and indicating device including a main component adapted for mounting in a cavity of a wall, and a cover plate fitted there over. The main component includes a frame or holder on which are mounted a plurality of operating members (referred to below) and those members have indicating elements exposed through, or slightly projecting through, openings in the cover plate. Document US 2003/038415 presents a sensor isolation system including a sensor, a package for the sensor, and a compliant interposer disposed between the sensor and the package and interconnecting the sensor to the package to isolate the sensor from thermal and mechanical stresses and yet at the same time providing a physical interconnect between the sensor and the package.